CVE-2026-29783
HighSummary
The shell tool within GitHub Copilot CLI versions prior to and including 0.0.422 can allow arbitrary code execution through crafted bash parameter expansion patterns. An attacker who can influence the commands executed by the agent can exploit these patterns to execute hidden commands.
Risk Assessment
The organization may be exposed to unauthorized code execution, potentially leading to serious security breaches and data loss. Exploitation of this vulnerability could allow attackers to gain control over the system.
Recommendation
It is recommended to update GitHub Copilot CLI to version 0.0.423 or later to mitigate this vulnerability. Additionally, conducting an audit of used scripts and commands is advisable to minimize risk.
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Original NVD description (English source)
The shell tool within GitHub Copilot CLI versions prior to and including 0.0.422 can allow arbitrary code execution through crafted bash parameter expansion patterns. An attacker who can influence the commands executed by the agent (e.g., via prompt injection through repository files, MCP server responses, or user instructions) can exploit bash parameter transformation operators to execute hidden commands, bypassing the safety assessment that classifies commands as "read-only." This has been patched in version 0.0.423. The vulnerability stems from how the CLI's shell safety assessment evaluates commands before execution. The safety layer parses and classifies shell commands as either read-only (safe) or write-capable (requires user approval). However, several bash parameter expansion features can embed executable code within arguments to otherwise read-only commands, causing them to appear safe while actually performing arbitrary operations. The specific dangerous patterns are ${var

